Sound listening device



p 1940- c HUENLICH SQUND LISTENING DEVICE Filed Oct. 28, 1937 INVENTOR, Charles fluenZzc/l/ BY 26 My Man/W TTORNEY Patented Sept. 24, 1940 UNITED STATES PATENT OFFICE SOUND LISTENING DEVICE Application October 28, 1937, Serial No. 171,442

4 Claims.

This invention relates to sound listening devices, and more particularly to improved means for controlling the volume of sound in such devices.

A listening device for conveying sound from a sound source to the ears of a listener may comprise a head set having earpieces adapted to engage the ears of the listener, and sound conveying means connecting each of the earpieces m to the sound source. In such devices it is customary to convey the sound from the sound source to within the vicinity of the listener by means of a single sound conveying tube. This tube then branches into separate sound conveying tubes which lead to the respective earpieces.

At the place of the branching there may be conveniently provided means for controlling the volume of sound admitted to each of the earpieces.

It is an object of my invention to provide at a particularly convenient point in sound listen ing devices simplified means for controlling the volume of sound admitted to either or both of the earpieces.

It is another object to provide easily operable means for adjusting the sound volume admitted to the separate ear-pieces so as to compensate for ear deficiencies.

It is another object to provide improved means conveniently accessible to the listener for controlling the volume of sound admitted to either or both of the earpieces.

It is another object to provide simplified means for controlling the volume of sound admitted to one earpiece in inverse proportion to that admitted to the other earpiece.

In the description of my invention reference is had to the accompanying drawing, of which:

Figure l is a view of a sound source and of a listening device therefor, showing, in section and to enlarged scale, one form of my invention as applied to the listening device;

Figure 2 is a cross-sectional view taken along the line 2-2 of Figure 1, with a portion shown in full; and

Figure 3 is a sectional view of a portion of a listening device showing a modified form of my invention as applied thereto.

Reference being had to Figure 1, there will be seen a sound source which, for illustrative pur- 50 poses, is shown as comprising a sound box I engaging a cylindrical record 2 such as is common in commercial phonographs. The sound box I is provided with a tubular extending element 3 which conveys the sound therefrom. The

55 volume of the sound may be controlled by a suitable manually operable valve, as indicated schematically by the numeral 4. The tubular element 3 is coupled to a tubular inlet 6 of a sound coupling unit 5 by means of a sound conveying tube 3', forming thereby a continuous sound duct from the sound box I to the sound coupling unit 5. In my invention the unit 5 may comprise a tubular inlet branching from a common junction point into two or more tubular outlets. For illustrating my invention, the 10 sound coupling unit 5 is shown as being forkshaped and comprising the tubular inlet 6 communicating with two tubular outlets l and 8 to form a continuous sound duct therebetween. The

tubular outlets 1 and 8 are coupled respectively 15 to the earpieces 9 and I0 by means of the respective sound conveying tubes 9 and ill. The earpieces 9 and H] are cup-shaped members and are adapted to engage the ears of the listener to transmit sound thereto. They are held suitably together as by a head band i i to form a head set A. The sound conveying tubes 3, 9' and ID are commonly made of flexible rubber tubing. The tubes 9 and I0 are appropriately of short length (8 to 10 inches) so that the sound coupling unit 25 5 is conveniently disposed with respect to the listener when the head set is put in place. At the place of the branching or bifurcation of the sound coupling unit 5 there may be appropriately located simplified means for controlling the sound volume admitted to either or both of the 80 earpieces 9 and I0. These means Will then be conveniently located so as to be readily accessible to the listener. It is with such means that my .invention is particularly concerned. 5

The fork-shaped sound coupling unit 5 is com- 3 prised of a short cylindrical member 12. It has apertures 6-, 'l" and 8' which may be radial from a central point 5'. There are provided in these apertures radially extendng tubes which form respectively the tubular inlet 6 and the tubular outlets I and 8. For illustrative purposes, the tubular outlets 1 and 8 are shown as being spaced about 135 from. the tubular inlet 6, but no limitation of my invention is intended thereby. In the cylindrical member [2 there is rotatably mounted a cylindrically shaped valve member Hi. The valve member I3 is provided with a shoulder II which rests slidably against the end face 12' of the member l2. It is retained in its operating position by means of a circular plate l5 threaded thereto and a spring washer l6 which is interposed between the rim portion of the plate l5 and the end face l2" of the member i2. There are provided in the valve member l3 intercommunicating radially extending apertures H to 24, inclusive, spaced at 45 intervals around the member H. The apertures l1, l8, l9, 2i and 24 have each a crosssectional area equal to that of the sound duct provided by the inlet 6 and outlets l and I of the unit 5; whereas the apertures 20, 22 and 23 have reduced cross-sectional areas. The apertures ll, l8 and [9 are adapted to come into alignment with the tubular inlet 6, the respective alignments being male at 45 intervals in the angular adjustment of the valve member l3. This adjustment may be performed manually by means of a knob 25 which is shown as being integral with the valve member H. For the respective alignments of apertures I1, 18 and I 9 with the tubular inlet 6, the apertures 20, 2| and 22 respectively register with the tubular outlet 7, and the apertures 22, 23 and 24 with the tubular outlet 8. For the position of valve member l3 which brings the aperture i! into alignment with the tubular inlet 6, the apertures 20 and 22, each of reduced cross-sectional area, respectively register with the tubular outlets and 8. Thus the volume of sound in each of the tubular outlets is reduced equally. When the valve member I3 is rotated 45 clockwise from the position just mentioned, to the position it occupies in; Figure l, aperture I8 is brought into alignment with the tubular inlet 6, whereas the aperture 2i is made to register with the tublar outlet 1, and the aperture 23, having a reduced cross-sectional area, with the tubular outlet 8. The sound volume in the tubular outlet 8 is then less than that in the tubular outlet 1. Similarly, when the valve member i3 is 1'0- tated clockwise through another 45 interval from the position it occupies in Figure l, the aperture I9 is brought into alignment with the tubular inlet 6 whereas the aperture 22, having a reduced cross-sectional area, is made to register with the tubular outlet 1 and the aperture 24 with the tubular outlet 8. In this case less sound volume is admitted in the tubular outlet 1 than in the tubular outlet 8. Thus, by the simple angular adjustment of the valve member l3, the sound volume may be controlled in either of the outlets, or in both of the outlets in equal proportion. Since the outlets are respectivelycoupled to earpieces the sound volume conveyed to the respective earpieces is controlled accordingly.

In Figure 3 there is shown a modified form of sound volume control means in which there is employed a cylindrical member |2a having radial apertures 6', I and 8'. There are also provided in these apertures radially extending tubes which form respectively the tubular inlet 6 and tubular outlets T and 8. The tubular outlets I and 8 are closer -to each other angularly than in the aforementioned case, being spaced by about 45 with respect to each other and equally angularly spaced away from the tubular inlet 6. The cylindrical valve member I3 is, in this modified form of my invention, altered and given the reference character [3a, being provided with only a single tapered aperture 26 extending diametrically therethrough. The smaller end 26' of the aperture 26 is adapted to come into alignment with either of the outlet apertures 7' and 8 or with portions of both. This smaller end 26' is preferably somewhat wider than either of the apertures I or 8 by at least as much as the distance between the adjacent sides of the apertures 'l' and 8, and is preferably less than the distance between the tar sides of the apertures 1' and I. The larger end 26" of the aperture 28 is oi. sumcient width to permit free opening of the tubular inlet i throughout the operating range of the rotating valve member "a. This arrangement permits a smooth control in the volume of sound admitted to the tubular outlets, or conveyed to the earpieces since they are directly coupled thereto. It permits also either of the tubular outets to be completely closed without obstructing the passageway to the other. Moreover, it permits equal sound volume to be obtained in the tubular outlets, or increased sound volume in either of the tubular outlets in proportion to the amount by which the other is diminished.

There is a significant advantage in discriminating between the sound volume admitted to the separate earpieces of a head set in a listening device. This is particularly true whenever the listener has deficient hearing in one or the other cars. In such cases the listener's hearing is improved by controlling the overall volume of sound from the sound source, as by the valve 4, and adjusting the volume control to the respective earpieces so as to favor the ear having the deficient hearing while yet providing suilicient volume of sound to the normal ear. It is in such cases that I find it highly desirable to have a line degree of control in the volume of sound admitted to the separate earpieces of a head set as a means for compensating for such hearing deficiencies. This is very desirable in cases where the listener is required to listen attentively over prolonged periods such as is commonly true with operators who transcribe recorded dictation in commercial phonographs.

By placing the means for controlling the sound volume to the tubular outlets l and 8 at the place of branching of the sound coupling unit 5, I am enabled to use simplified mechanical arrangements for effecting such control. Due to the fact that the coupling unit 5 is normally conveniently placed with respect to the listener, this is a readily accessible place for a manually operable volume control.

Although I have described my invention in terms of specific embodiments, it will be understood that many modifications thereof are possible without departing from the scope of my invention. I have, for instance, illustrated my invention with a fork-shaped coupling unit and a single head set having two earpieces but it is obvious that the coupling unit need not be forkshaped, and that the unit may have any plurality of outlets branching off from the inlet in some one region, which outlets may be connected to a plurality of earpieces. Such and other modifications do not necessarily depart from the spirit of my invention which I undertake to express in the following claims.

I claim:

1. In a sound listening device, a sound tube having a plurality of branches leading from a common junction point, and a valve member rotatably mounted in said tube at said junction point and provided with intercommunicating apertures of predetermined and diiferent cross-sectional areas adapted for selective alignment with said tube and branches.

2. In a sound listening device, a sound coupling unit having a sound inlet and a plurality of sound outlets branching from a common junction point, a valve member disposed at said junction point and provided with a plurality of in- 1 tercommunicating apertures 01 a number exceeding the sum of said inlet and outlets and of predetermined and different cross-sectional areas, and manual means for moving said valve member relative to said coupling unit to selectively align said apertures with said inlet and outlets.

3. In a sound listening device, a sound tube having a plurality of branches leading from a common junction point and a valve member rotatably mounted in said tube at said junction point and provided with a tapered aperture extending therethrough for progressively discriminating between the volume of sound conveyed from said tube to its branches, the smaller end of said aperture having a greater width than the separation between the bores of the branches and less width than the sum of said separation and the width or the bore of one of the branches, and the larger end of said aperture having a width substantially equal to the sum of the width of the bores of said tube and one of the branches.

4. In a sound listening device, a sound tube having a plurality of branches leading from a common junction point and from a common plane, a valve member disposed at the place of said branching and having intercommunicating radially extending apertures of predetermined and different cross-sectional areas, said apertures being arranged so that their axes lie in a common plane, and manual means for moving said valve member relative to said sound tube to control the volume of sound conveyed to said branches.

CHARLES HUENLICH. 

